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Paleontology

Fossil Rodent Teeth Add North American Twist To Caribbean Mammals Origin Story (Paleontology)

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Two fossil teeth from a distant relative of North American gophers have scientists rethinking how some mammals reached the Caribbean Islands.

The teeth, excavated in northwest Puerto Rico, belong to a previously unknown rodent genus and species, now named Caribeomys merzeraudi. About the size of a mouse, C. merzeraudi is the Caribbean’s smallest known rodent and one of the region’s oldest, dating back about 29 million years.

It also represents the first discovery of a Caribbean rodent from a North American lineage, a finding that complicates an idea that has persisted since Darwin – that land-dwelling mammals colonized the islands from South America. The presence of C. merzeraudi in Puerto Rico suggests a second possibility: Some species may have rafted from North America.

The tiny rodent joins two other types of animals, an extinct rhinoceros-like species and bizarre, venomous shrews known as Solenodons, as the only known examples of Caribbean land-dwelling mammals with North American roots.

“This discovery demonstrates that overwater dispersal from North America was also a potential pathway to the Caribbean,” said study co-author Jorge Velez-Juarbe, associate curator of mammalogy at the Natural History Museum of Los Angeles County. “This challenges what we thought we knew about the origins of Antillean terrestrial mammals.”

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illustration of position of rodent teeth in model skull
This artist’s reconstruction shows the likely position of these fossil molars in Caribeomys merzeraudi’s skull. These two teeth are the only evidence of this species thus far.ILLUSTRATION COURTESY OF JORGE VELEZ-JUARBE
image of CT scan of rodent molar
Researchers believe this molar came from an old adult because of its advanced state of wear. This tooth is the holotype of Caribeomys merzeraudi, meaning that the species description is based on this specimen.IMAGE COURTESY OF THE PALAEONTOLOGICAL ASSOCIATION
image of CT scan of rodent molar
This tooth likely belonged to a newborn. A thick layer of enamel helped preserve the teeth during fossilization.IMAGE COURTESY OF THE PALAEONTOLOGICAL ASSOCIATION

While Caribbean ecotourism brochures generally don’t feature splashy images of rats, the islands were once home to a rich representation of rodents, including spiny rats, chinchillas, rice rats and hutias – all descendants of South and Central American forebears.

Fossil and molecular evidence suggest these rodents arrived in the islands in multiple waves over time, though how they got there – whether by scurrying over an ancient land bridge, island-hopping or rafting – has been hotly contested. The paucity of fossils from the early years of the Caribbean Islands further obscures the picture of the region’s past biodiversity.

Caribeomys merzeraudi’s teeth were so unusual that researchers initially struggled to discern what kind of animal they had come from, said study co-author Lazaro Viñola Lopez, a doctoral student in vertebrate paleontology at the Florida Museum of Natural History.

“We didn’t know what it was for several months,” he said. “We wondered whether this could be some other rodent from the Caribbean or even some kind of strange fish. It was so puzzling because they’re not similar to anything else we had found in that region.”

paleontologists excavating fossils
Scientists on the research team excavate fossils from a layer of grey, silty claystone in Puerto Rico: from top, Lazaro Viñola Lopez, Jorge Velez-Juarbe, François Pujos and Laurent Marivaux. Velez-Juarbe was part of a group of undergraduate students that discovered the site in 2006. He has returned to it each year.PHOTO COURTESY OF PIERRE-OLIVIER ANTOINE

The team eventually pinpointed several tooth characteristics that are hallmarks of rodents known as geomorphs, a group that includes kangaroo rats, pocket mice and gophers. Caribeomys merzeraudi is the first geomorph found outside North America.

An exceptionally thick layer of tooth enamel, among other features, sets C. merzeraudi apart from its relatives and could indicate these rodents belonged to a distinct West Indian branch that evolved in isolation over several million years, Viñola Lopez said.

Scientists found the teeth while screen-washing sediment collected from a river outcrop in San Sebastian, a site that has yielded fossil sharks and rays, fish, turtles, a gharial, sea cows and the oldest known frog in the Caribbean, a coquí. In 2019, the team excavated fossil evidence of two large chinchillas, which likely grew up to 30 pounds. These South American rodents once shared Puerto Rico with the humble C. merzeraudi, which weighed less than a quarter pound.

Today, hutias, bats and Solenodons are the “last survivors of what was once a much more diverse group of Caribbean mammals” that included sloths and primates, Velez-Juarbe said.

Discovering C. merzeraudi opens up the tantalizing possibility that Caribbean mammals with North American origins may not be as exceptional as previously thought, Viñola Lopez said. But there’s only one way to find out: “Go back to the locality and see what else we can find.”

The researchers published their findings in Papers in Palaeontology.

Featured image: A paleontologist stands on an outcrop next to the Rio Guatemala, which flows through the township of San Sebastian, Puerto Rico. The site has yielded an abundance of fossils. including two teeth that belonged to a rodent with North American roots.PHOTO COURTESY OF JORGE VELEZ-JUARBE

Reference: Marivaux, L., Vélez-Juarbe, J., Viñola López, L.W., Fabre, P.-H., Pujos, F., Santos-Mercado, H., Cruz, E.J., Grajales Pérez, A.M., Padilla, J., Vélez-Rosado, K.I., Cornée, J.-J., Philippon, M., Münch, P. and Antoine, P.-O. (2021), An unpredicted ancient colonization of the West Indies by North American rodents: dental evidence of a geomorph from the early Oligocene of Puerto Rico. Pap Palaeontol. https://doi.org/10.1002/spp2.1388

Provided by Florida Museum

Paleontology

635 Million-year-old Fungi-like Microfossil that Bailed Us out of an Ice Age Discovered (Paleontology)

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When you think of fungi, what comes to mind may be a crucial ingredient in a recipe or their amazing ability to break down dead organic matter into vital nutrients. But new research by Shuhai Xiao, a professor of geosciences with the Virginia Tech College of Science, and Tian Gan, a visiting Ph.D. student in the Xiao lab, highlights yet another important role that fungi have played throughout the Earth’s history: helping the planet recover from an ice age.

A team of scientists from Virginia Tech, the Chinese Academy of Sciences, Guizhou Education University, and University of Cincinnati has discovered the remains of a fungi-like microfossil that emerged at the end of an ice age some 635 million years ago. It is the oldest terrestrial fossil ever found. To put it into perspective, this microfossil predates the oldest dinosaurs about three times over.

Their findings were published in Nature Communications on Jan. 28.

The fossil was found in small cavities within well-studied sedimentary dolostone rocks of the lowermost Doushantuo Formation in South China. Although the Doushantuo Formation has provided a plethora of fossils to date, researchers did not expect to find any fossils toward the lower base of the dolostones.

But against all odds, Gan found a few long, thread-like filaments – one of the key characteristics of fungi.

“It was an accidental discovery,” said Gan. “At that moment, we realized that this could be the fossil that scientists have been looking for a long time. If our interpretation is correct, it will be helpful for understanding the paleoclimate change and early life evolution.”

This discovery is key for understanding multiple turning points throughout Earth’s history: the Ediacaran period and the terrestrialization of fungi.

When the Ediacaran period began, the planet was recovering from a catastrophic ice age, also known as the “snowball Earth.” At that time, ocean surfaces were frozen to a depth of more than a kilometer and it was an incredibly harsh environment for virtually any living organism, except for some microscopic life that managed to thrive. Scientists have long wondered how life ever returned to normalcy – and how the biosphere was able to grow larger and more complex than ever before.

With this new fossil in hand, Tian and Xiao are certain that these microscopic, low profile cave dwellers played numerous roles in the reconditioning of the terrestrial environment in the Ediacaran time. One role involved their formidable digestive system.

Fungi have a rather unique digestive system that plays an even greater role in the cycling of vital nutrients. Using enzymes secreted into the environment, terrestrial fungi can chemically break down rocks and other tough organic matter, which can then be recycled and exported into the ocean.

“Fungi have a mutualistic relationship with the roots of plants, which helps them mobilize minerals, such as phosphorus. Because of their connection to terrestrial plants and important nutritional cycles, terrestrial fungi have a driving influence on biochemical weathering, the global biogeochemical cycle, and ecological interactions,” said Gan.

Although previous evidence stated that terrestrial plants and fungi formed a symbiotic relationship around 400 million years ago, this new discovery has recalibrated the timeline of when these two kingdoms colonized the land.

“The question used to be: ‘Were there fungi in the terrestrial realm before the rise of terrestrial plants’,” said Xiao, an affiliated faculty member of the Fralin Life Sciences Institute and the Global Change Center. “And I think our study suggests yes. Our fungus-like fossil is 240 million years older than the previous record. This is, thus far, the oldest record of terrestrial fungi.”

Now, new questions have arisen. Since the fossilized filaments were accompanied by other fossils, Gan will set out to explore their past relationships.

“One of my goals is to constrain the phylogenetic affinities of these other types of fossils that are associated with the fungal fossils,” said Gan.

Xiao is thrilled to tackle the environmental aspects of these microorganism. Sixty years ago, few believed that microorganisms, like bacteria and fungi, could be preserved as fossils. Now that Xiao has seen them with his very eyes, he plans to learn more about how they have been virtually frozen in time.

“It is always important to understand the organisms in the environmental context,” said Xiao. “We have a general idea that they lived in small cavities in dolostone rocks. But little is known about how exactly they lived and how they were preserved. Why can something like fungi, which have no bones or shells, be preserved in the fossil record?”

However, it can’t be said for sure if this fossil is a definitive fungus. Although there is a fair amount of evidence behind it, the investigation into these microfossils is ongoing.

“We would like to leave things open for other possibilities, as a part of our scientific inquiry,” said Xiao. “The best way to put it is that perhaps we have not disapproved that they are fungi, but they are the best interpretation that we have at the moment.”

Three distinct groups and labs at Virginia Tech were crucial for the identification and timestamping of this fossil. The Confocal Laser Scanning and Microscopy lab at the Fralin Life Sciences Institute helped Tian and Xiao perform initial analysis that prompted further investigation at the University of Cincinnati.

The Department of Biological Sciences’ Massey Herbarium, which houses over 115,000 specimens of vascular plants, fungi, bryophytes, and lichens, provided modern fungal specimens for comparison with the fossils.

The team called in technicians to conduct geochemical analysis using Secondary Ion Mass Spectrometry, which ionize nanomoles of material from small areas that are a fraction the thickness of a hair strand, to analyze the isotopic abundance of sulfur-32 and sulfur-34 in order to understand the fossilization environment.

Advanced computerized tomography was crucial to getting the 3D morphology of the filaments, which are just a few micrometers thick. And a combination of Focused Ion Beam Scanning Electron Microscopy and Transmission Electron Microscopy allowed researchers to cut samples with surgical precision and take an even closer look at every nanometer of the filaments.

“This wasn’t a single person or even a single lab that did this work,” said Xiao.

Xiao also emphasized the importance of interdisciplinary research in this study and many others.

“It’s very important to encourage the next generation of scientists to be trained in an interdisciplinary light because new discoveries always happen at the interface of different fields,” said Xiao. (VIRGINIA TECH)

The first author Gan Tian and one of the corresponding authors Luo Taiyi are affiliated with the Institute of Geochemistry of the Chinese Academy of Sciences (IGCAS). 

Featured image: Microscopic image of the fungus-like filamentous microfossils. Credit: Andrew Czaja of University of Cincinnati.

Reference: Gan, T., Luo, T., Pang, K. et al. Cryptic terrestrial fungus-like fossils of the early Ediacaran Period. Nat Commun 12, 641 (2021). https://doi.org/10.1038/s41467-021-20975-1

Provided by Chinese Academy of Sciences

Paleontology

Rare Fossilized Algae, Discovered Unexpectedly, fill in Evolutionary Gaps (Paleontology)

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When geobiology graduate student Katie Maloney trekked into the mountains of Canada’s remote Yukon territory, she was hoping to find microscopic fossils of early life. Even with detailed field plans, the odds of finding just the right rocks were low. Far from leaving empty-handed, though, she hiked back out with some of the most significant fossils for the time period.

Eukaryotic life (cells with a DNA-containing nucleus) evolved over two billion years ago, with photosynthetic algae dominating the playing field for hundreds of millions of years as oxygen accumulated in the Earth’s atmosphere. Geobiologists think that algae evolved first in freshwater environments on land, then moved to the oceans. But the timing of that evolutionary transition remains a mystery, in part because the fossil record from early Earth is sparse.

Maloney’s findings were published yesterday in Geology. She and her collaborators found macroscopic fossils of multiple species of algae that thrived together on the seafloor about 950 million years ago, nestled between bacterial mounds in a shallow ocean. The discovery partly fills in the evolutionary gap between algae and more complex life, providing critical time constraints for eukaryotic evolution.

Although the field site was carefully chosen by Maloney’s field team leader, sedimentologist Galen Halverson, who has worked in the region for years, the discovery was an unexpected stroke of luck.

“I was thinking, ‘maybe we’ll find some microfossils,’” Maloney said. The possibility of finding larger fossils didn’t cross her mind. “So as we started to find well-preserved specimens, we stopped everything and the whole team gathered to collect more fossils. Then we started to find these big, complex slabs with hundreds of specimens. That was really exciting!”

Determining if traces like the ones Maloney found are biogenic (formed by living organisms) is a necessary step in paleobiology. While that determination is ultimately made in the lab, a few things tipped her off in the field. The traces were very curvy, which can be a good indicator of life, and there were visible structures within them. The fact that there were hundreds of them twisted together sealed the deal for her.

Few people would likely have noticed the fossils that day.

On the right, a slab of gray shale sample. Two black boxes mark places where fossilized algae are present; those are shown on the left. The fossils are reddish-brown marks, curving and broken into segments, on a gray rock background. © Photo by K. Maloney.

“We were really lucky that Katie was there to find them because at first glance, they don’t really look like anything,” Maloney’s advisor, Marc Laflamme, said. “Katie is used to looking at very weird looking fossils, so she has a bit of an eye for saying, ‘This is something worth checking out.’”

Maloney and her colleagues in the field wrestled the heavy slabs into their helicopter for safe transport back to the lab at the University of Toronto–Mississauga. She, Laflamme, and their collaborators used microscopy and geochemical techniques to confirm that the fossils were indeed early eukaryotes. They then mapped out the specimens’ cellular features in detail, allowing them to identify multiple species in the community.

While Maloney and her coauthors were writing up their results, they were confident they had found the first macroscopic specimens from this critical time period. During the peer review process, though, they received word from a collaborator that another group in China had made a similar discovery at about the same time—macrofossils from a similar period. That did not dissuade them.

“What’s a few hundred million years between friends?” Laflamme laughed. “I think our fossils have more detail, which makes them easier to interpret… They’re beautiful. They’re huge, they’re well detailed, there’s anatomy. Your eyes are just drawn to them.”

Ultimately, having two sets of macrofossils from approximately the same time can only improve the timeline of eukaryotic evolution, serving as critical calibration points for DNA-based biologic dating techniques. The new fossils also push back the time when algae were living in marine environments, indicating that evolution had already occurred in lakes on land. But for Maloney, an expert in sedimentology, they also raise questions about what gets preserved in the rock record and why.

“Algae became really important early on because of their role in oxygenation and biogeochemical cycles,” Maloney said. “So why does it take them so long to show up reliably in the fossil record? It’s definitely making us think more about animal ecosystems and whether or not we’re seeing the whole picture, or if we’re missing quite a bit from a lack of preservation.”

The whole project has been engaging for Maloney, who pivoted to algae from more recent biota. “I never expected to be fascinated by algae,” she said. “But I was pleasantly surprised as I started investigating modern algae, finding what an important role they play in sustainability and climate change—all these big issues that we’re dealing with today. So it’s been amazing contributing to algae’s origin story.”

Featured image: The field team breaks for lunch after a morning of fossil-hunting in the Wernecke Mountains of the Yukon Territory in Canada. The ridge they’re sitting on is made of shales of the Dolores Creek Formation, where Maloney and her colleagues collected fossilized algae. (Photo: K. Maloney.)

Reference: Katie M. Maloney, Galen P. Halverson, James D. Schiffbauer, Shuhai Xiao, Timothy M. Gibson, Maxwell A. Lechte, Vivien M. Cumming, Alexie E.G. Millikin, Jack G. Murphy, Malcolm W. Wallace, David Selby, Marc Laflamme; New multicellular marine macroalgae from the early Tonian of northwestern Canada. Geology 2021; doi: https://doi.org/10.1130/G48508.1 URL: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G48508.1/595633/New-multicellular-marine-macroalgae-from-the-early

Provided by Geological Society of America

Paleontology

New Australian Fossil Lizard (Paleontology)

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Oldest skink named after eminent biology professor

Some of Australia’s most famous animals – wombat, platypus, kangaroos and the extinct marsupial tiger thylacine – have been traced back to their fossil ancestors in remarkable finds in central South Australia.

Now a remote expedition to a large inland salt lake in 2017 has sifted through remains unearthed in Namba Formation deposits to describe a tiny new skink, an ancestor of Australia’s well-known bluetongue lizards – to be named in honour of world-renown Flinders University lizard researcher Professor Mike Bull.

The new species, unveiled in the Royal Society’s Open Science today, is described as Australia’s oldest – a 25 million-year-old skink named Proegernia mikebulli after the late Flinders University Professor Mike Bull.

It was found by Flinders University and South Australian Museum palaeontologists and volunteers at a rich fossil site on Lake Pinpa located on the 602,000 square hectare Frome Downs Station, seven hours drive north of capital city Adelaide.

Following the crusted shoreline of a salt lake, the team homed in on a cross section of sediments where fossil excavations of ancestors of koala, a predatory bird, and fragments of a thylacine were previously unearthed. Remains of prehistoric fish, platypus, dolphins and crocodilians have also been found nearby.

“It was 45°C in the shade that day and hard work digging through the clay, but it was definitely worth it once the tiniest of bone fragments turned out to be those of the oldest Australian skink,” says lead author palaeo-herpetologist Dr Kailah Thorn, who conducted the research at Flinders University as part of her PhD.

Lead author Dr Kailah Thorn, who conducted the research as part of her PhD at Flinders University, South Australia © Kailah Thorn

The once-verdant interior of Australia is considered the cradle of Australia’s unique fauna and in particular its reptile diversity.

“Fossil lizards are often too small to be identified when you’re in the field. Lizard skulls are made of more than 20 individual bones that all disarticulate when they fossilise,” says Dr Thorn, who now works as curator of the Edward de Courcy Clarke Earth Sciences Museum at the University of Western Australia.

The discovery of the tiny fossil lizards in an area the size of one million soccer fields was enabled by building an understanding of the geology of the region, and targeting fossiliferous bands of silt to thoroughly sieve and sort back at the lab, she explains.

“These lizard fossils owe their discovery to the patient sorting of tiny bones,” says lead author, vertebrate palaeontologist Flinders University Associate Professor Trevor Worthy. “A teaspoon holds hundreds of tiny bones – all revealed in translucent splendour under a microscope.”

“Once every 30 spoons something else is found among the fish – usually a tiny mammal tooth. But the 2017 discovery of the oldest skink was a golden moment for a palaentologist,” he says.

Tiny fossil bones from the Lake Pinpa site. © Flinders University

When researchers placed the fossil in the evolutionary tree of lizards, it was found to be an early member of the Australian skink subfamily Egerniinae – the group now encompassing bluetongues, sleepy lizards (shinglebacks), land mullets and spiny-tailed skinks.

The newly described lizard Proegernia mikebulli is named after the late Flinders University Professor Mike Bull, who passed away suddenly in late 2016.

Inspired generations of Australian herpetologists, Professor Bull’s wide-ranging research career centred on social skinks from the Egerniinae subfamily, their behaviour, parasites, and conservation.

“Our colleague Professor Bull’s long-term ecological studies of sleepy lizards were a massive contribution to biology,” says co-author Matthew Flinders Professor Mike Lee (Flinders University / SA Museum).

“The fossil record is essentially data from a long-term natural ecological study, so its fitting that this fossil lizards is named after in honour of Mike.”

‘A new species of Proegernia from the Namba Foundation in South Australia and the early evolution and environment of Australian egerniine skinks’ (2021) by KM Thorn, MH Hutchinson, MSY Lee, N Brown, AB Camens and TH Worthy has been published in Royal Society Open Science DOI 10.1098/rsos.201686

Timelapse video and high-res photos available upon request. Also see https://youtu.be/7uTeCwLyFWY

Featured image: Swamp Skink (Lissolepis coventryi), which is probably the living lizard most similar to the new fossil. Photo: Dr Mark Hutchinson, SA Museum / Flinders University, a co-author. © Photo: Dr Mark Hutchinson, SA Museum / Flinders University

Provided by Flinders University

Paleontology

Ancient Wolf Pup Mummy Uncovered in Yukon Permafrost (Paleontology)

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While water blasting at a wall of frozen mud in Yukon, Canada, a gold miner made an extraordinary discovery: a perfectly preserved wolf pup that had been locked in permafrost for 57,000 years. The remarkable condition of the pup, named Zhùr by the local Tr’ondëk Hwëch’in people, gave researchers a wealth of insights about her age, lifestyle, and relationship to modern wolves. The findings appear December 21 in the journal Current Biology.

This photo shows an x-ray view of the wolf pup. © Government of Yukon

“She’s the most complete wolf mummy that’s ever been found. She’s basically 100% intact–all that’s missing are her eyes,” says first author Julie Meachen, an associate professor of anatomy at Des Moines University. “And the fact that she’s so complete allowed us to do so many lines of inquiry on her to basically reconstruct her life.”

One of the most important questions about Zhùr that the researchers sought to answer was how she ended up preserved in permafrost to begin with. It takes a unique combination of circumstances to produce a permafrost mummy.

“It’s rare to find these mummies in the Yukon. The animal has to die in a permafrost location, where the ground is frozen all the time, and they have to get buried very quickly, like any other fossilization process,” says Meachen. “If it lays out on the frozen tundra too long it’ll decompose or get eaten.”

This photo shows the wolf pup as she was found. © Government of Yukon

Another important factor is how the wolf died. Animals that die slowly or are hunted by predators are less likely to be found in pristine condition. “We think she was in her den and died instantaneously by den collapse,” says Meachen. “Our data showed that she didn’t starve and was about 7 weeks old when she died, so we feel a bit better knowing the poor little girl didn’t suffer for too long.”

In addition to learning how Zhùr died, the team were also able to analyze her diet. As it turns out, her diet was heavily influenced by how close she lived to water. “Normally when you think of wolves in the Ice Age, you think of them eating bison or musk oxen or other large animals on land. One thing that surprised us was that she was eating aquatic resources, particularly salmon.”

Analyzing Zhùr’s genome also confirmed that she is descended from ancient wolves from Russia, Siberia, and Alaska, who are the ancestors of modern wolves as well. Although analyzing Zhùr gave the researchers many answers about wolves of the past, there remain some outstanding questions about Zhùr and her family.

This photo shows a closeup of the wolf pup’s head, showing her teeth. © Government of Yukon

“We’ve been asked why she was the only wolf found in the den, and what happened to her mom or siblings,” says Meachen. “It could be that she was an only pup. Or the other wolves weren’t in the den during the collapse. Unfortunately, we’ll never know.”

The specimen holds special significance for the local Tr’ondëk Hwëch’in people, who have agreed to place Zhùr on display at the Yukon Beringia Interpretive Centre in Whitehorse. She is cleaned and conserved so she will stay intact for years to come, allowing her to travel to other Yukon locations as well. And the research team predicts there may be more and more permafrost mummies found in the coming years.

“One small upside of climate change is that we’re going to find more of these mummies as permafrost melts,” says Meachen. “That’s a good way for science to reconstruct that time better, but it also shows us how much our planet is actually warming. We really need to be careful.”

Reference: Julie Meachen, Matthew J. Wooller, Benjamin D. Barst, Elizabeth Hall, Susan Hewitson, Grant Zazula, “A mummified Pleistocene gray wolf pup”, Current Biology, Vol. 30, Issue 24, 2020. https://doi.org/10.1016/j.cub.2020.11.011 https://www.cell.com/current-biology/fulltext/S0960-9822(20)31686-9?utm_source=EA

Provided by Cell Press

Astronomy

The Milky Way Primordial History and Its Fossil Findings (Astronomy)

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Just as archaeologists dig hoping to find traces of the past, an international group of astrophysicists managed to get into the thick cloud of dust around the centre of the Milky Way (also known as the bulge) discovering primordial clumps of gas and stars never found so far. They named this new class of stellar system “Bulge Fossil Fragments”. A research team led by Francesco Ferraro (Department of Physics and Astronomy “Augusto Righi” at the University of Bologna and member of the National Institute for Astrophysics – INAF) carried out a study published in Nature Astronomy.

Panoramic view of the Milky Way (Credit: ESO/S. Brunier) with the location of the two Bulge Fossil Fragments discovered so far (Liller 1 and Terzan 5) highlighted. © F. R. Ferraro / C. Pallanca (University of Bologna)

Researchers found out about this new class while analyzing Liller 1. The latter is a stellar system in the Milky Way bulge that for more than 40 years has been classified as a “globular cluster”, i.e. a system composed of millions of same-aged stars (the Milky Way has at least 150 globular clusters). However, researchers observed Liller 1 closely and found out that its real identity is actually more fascinating than so far believed. Indeed, Liller 1 is a fossil fragment of one of the giant stellar clumps that, approximately 12 billion years ago, merged to form the central region (bulge) of the Milky Way.

“Our results clearly show that Liller 1 is not a globular cluster, but a much more complex object”, says Professor Francesco Ferraro, first author and coordinator of the study. “It is a stellar relic, a fossil finding that contains the history of the Milky Way formation”.

A VALIDATING RESULT

The existence of “cosmic findings” had already been suggested when researchers discovered a similar object, Terzan 5, some years ago. Terzan 5 looked like a globular cluster within our galaxy bulge, but, at a closer analysis, its features were not consistent with those of other globular clusters.

However, an isolated case is just an intriguing anomaly. This is why Liller 1 is so important. Terzan 5 and Liller 1 shared features confirm the existence of a new class of stellar systems unidentified until today.

FOSSIL FRAGMENTS

Which are the feature of the Bulge Fossil Fragments? These objects are disguised as globular clusters, but are fundamentally different, if one looks at the age of the stars composing them. Two stellar populations are in these systems: one is as old as the Milky Way – it formed 12 billion years ago – and the other one is much younger. On the one hand, this shows that these stellar systems appeared during the Milky Way early stages of formation; on the other hand, it demonstrates that they are able to engender multiple events of stellar generation.

“The features of Liller 1 and Terzan 5 stellar populations suggest that both systems formed at the same time of the Milky Way”, explains one of the authors of the study, Barbara Lanzoni, Professor at the University of Bologna and INAF member. “Younger stellar populations are richer in iron and tend to cluster in the central areas of the bulge. Indeed, this is in line with a context of self-enrichment in which the gas ejected by older stars forms new ones”.

BEYOND THE CLOUDS

Getting to these findings was anything but easy. Liller 1 is located in one of the most obscured regions of our galaxy, where thick clouds of interstellar dust dim starlight making it up to 10,000 times fainter. The only way of getting through these clouds is infrared light. This is why researchers chose Gemini South to perform the inspection of Liller 1. Gemini South is a powerful telescope with a diameter of 8 meters able to compensate for the distortions in stellar images caused by the atmosphere of the Earth.

The sharpness of Gemini South images is unparalleled. Thanks to these incredible pictures, researchers could do a detailed preliminary analysis of Liller 1 stellar population. Despite this preliminary analysis, researchers had still some work to do to have a complete picture of the composition of this stellar system. Indeed, they needed to know if all the stars shown by those images belonged to Liller 1, or if some of them were simply in the same line of sight, but did not belong to it. They managed to solve this issue by resorting to further observations performed through the Hubble Space Telescope.

“After having combined the two sets of images, we removed the stars that did not belong to Liller 1 and finally had a clear and detailed picture of this stellar system”, says Cristina Pallanca, a researcher at the University of Bologna and INAF member who co-authored the study. “Our results surprised us: Liller 1 hosts at least two stellar populations with dramatically different ages, the oldest having formed about 12 billion years ago, the same time the Milky Way formed; the second one, much younger, having formed just 1-2 billion years ago”.

A discovery that is remarkably similar to what they found out about Terzan 5, which similarly hosts one stellar population as old as the Milky Way and a much younger one (4.5 billion years).

“The discovery that Liller 1 and Terzan 5 share very similar features allowed for the identification of a new class of stellar systems originated from some ancestors that were massive enough to retain the gas ejected by supernovas. What we observed are just some fragments of these massive structures”, adds Emanuele Dalessandro, a researcher at INAF – Space Science Observatory (OAS) in Bologna and co-author of the study.

This then confirmed the existence of the “Bulge Fossil Fragments”, i.e. stellar systems composed of the relics of massive primordial objects that, 12 billion years ago, gave birth to the Milky Way.

“The history of the Milky Way is written in these fossil remains. The latter are tokens of an age during which the Universe was very young, just 1 billion years old”, concludes professor Ferraro. “Now we need to go deeper. Thanks to the discovery of these fossil remains we can start reading the history of the Milky Way and maybe re-define our knowledge about the formation of the bulge”.

THE AUTHORS OF THE STUDY

“A new class of fossil fragments from the hierarchical assembly of the Galactic bulge” is the title of this study published in Nature Astronomy. The researchers involved in this study are Francesco R. Ferraro, Cristina Pallanca, Barbara Lanzoni, Chiara Crociati and Alessio Mucciarelli from the Department of Physics and Astronomy “Augusto Righi” of the University of Bologna and INAF. Emanuele Dalessandro and Livia Origlia form the INAF also participated in the study.

References: Ferraro, F.R., Pallanca, C., Lanzoni, B. et al. A new class of fossil fragments from the hierarchical assembly of the Galactic bulge. Nat Astron (2020). https://www.nature.com/articles/s41550-020-01267-y https://doi.org/10.1038/s41550-020-01267-y

Provided by University of Bologna

Paleontology

Henderson Island Fossils Reveal New Polynesian Sandpiper Species (Paleontology)

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Fossil bones collected in the early 1990s on Henderson Island, part of the Pitcairn Group, have revealed a new species of Polynesian sandpiper.

The Henderson Sandpiper, a small wading bird that has been extinct for centuries, is described in an article in the Zoological Journal of the Linnean Society published last week.

The extinct Kiritimati Sandpiper, Prosobonia cancellata – a close cousin of the newly discovered Prosobonia sauli. ©Illustration by George Edward Lodge, 1907

The newly-described bird is formally named Prosobonia sauli after Cook Islands-based ornithologist and conservationist Edward K Saul.

A team of researchers from New Zealand, Australia, Denmark, Switzerland, the Netherlands and China, led by Canterbury Museum Research Curator Natural History Dr Vanesa De Pietri, described the Henderson Sandpiper from 61 fossilised bones cared for by the Natural History Museum at Tring in England.

Canterbury Museum Visiting Researcher Dr Graham Wragg collected the bones from caves and overhangs on Henderson Island in 1991 and 1992 during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands.

Prosobonia sauli is the fifth known species of Polynesian sandpiper. All but one of the species, the endangered Tuamotu Sandpiper (Prosobonia parvirostris), are extinct.

“We think Prosobonia sauli probably went extinct soon after humans arrived on Henderson Island, which archaeologists estimate happened no earlier than the eleventh century,” says Dr De Pietri.

“It’s possible these humans brought with them the Polynesian rat, which Polynesian sandpiper populations are very vulnerable to.”

DNA of the living Tuamotu Sandpiper and the extinct Tahiti Sandpiper (Prosobonia leucoptera), which is known only from a skin in the Naturalis Biodiversity Center in the Netherlands, was used to determine how Polynesian sandpipers are related to other wading birds.

“We found that Polynesian sandpipers are early-diverging members of a group that includes calidrine sandpipers and turnstones. They are unlike other sandpipers in that they are restricted to islands of the Pacific and do not migrate,” says Dr De Pietri.

Comparisons with the other two extinct Polynesian sandpiper species, the Kiritimati Sandpiper (Prosobonia cancellata) and the Mo’orea Sandpiper (Prosobonia ellisi), are complicated. These birds are known only from illustrations primarily by William Wade Ellis, an artist and Surgeon’s Mate on Captain James Cook’s third expedition, who probably saw the birds alive in the 1770s.

The Henderson Island Sandpiper bones were excavated from caves during the Sir Peter Scott Commemorative Expedition in the early 1990s. Canterbury Museum Visiting Researcher Dr Graham Wragg, one of the paper’s co-authors, is second from left in this photo. ©Supplied

Compared to the Tuamotu Sandpiper, its geographically closest cousin, the Henderson Sandpiper had longer legs and a wider, straighter bill, indicating how it foraged for food. It probably adapted to the habitats available on Henderson Island, which are different to those on other islands where Polynesian sandpipers were found.

Henderson Island is the largest island in the Pitcairn Group, in the middle of the South Pacific Ocean. It has been uninhabited since around the fifteenth century and was designated a World Heritage Site by the United Nations in 1988.

Dr Paul Scofield, Canterbury Museum Senior Curator Natural History and one of the study’s co-authors, says Henderson Island is home to a number of unique species, a handful of which are landbirds like the Henderson Sandpiper.

“The island is really quite remarkable because every landbird species that lives there, or that we know used to live there, is not found anywhere else,” he says.

Dr De Pietri says the study shows the need to protect the one remaining Polynesian sandpiper species, the Tuamotu Sandpiper.

“We know that just a few centuries ago there were at least five Polynesian sandpiper species scattered around the Pacific. Now there’s only one, and its numbers are declining, so we need to ensure we look after the remaining populations.”

References: Vanesa L De Pietri, Trevor H Worthy, R Paul Scofield, Theresa L Cole, Jamie R Wood, Kieren J Mitchell, Alice Cibois, Justin J F J Jansen, Alan J Cooper, Shaohong Feng, Wanjun Chen, Alan Jd Tennyson, Graham M Wragg, A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia, Zoological Journal of the Linnean Society, , zlaa115, https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlaa115/5959945?redirectedFrom=fulltext https://doi.org/10.1093/zoolinnean/zlaa115

Provided by Canterbury Museum

Paleontology

The First Duckbill Dinosaur Fossil From Africa Hints At How Dinosaurs Once Crossed Oceans (Paleontology)

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The first fossils of a duckbilled dinosaur have been discovered in Africa, suggesting dinosaurs crossed hundreds of kilometres of open water to get there.

Duckbill dinosaurs evolved in north America, spreading to South America, Asia, Europe, and finally Africa. Credit: Raul Martin

The study, published in Cretaceous Research, reports the new dinosaur, Ajnabia odysseus, from rocks in Morocco dating to the end of the Cretaceous, 66 million years ago. Ajnabia was a member of the duckbill dinosaurs, diverse plant-eating dinosaurs that grew up to 15 meters long. But the new dinosaur was tiny compared to its kin – at just 3 meters long, it was as big as a pony.

Duckbills evolved in North America and eventually spread to South America, Asia, and Europe. Because Africa was an island continent in the Late Cretaceous, isolated by deep seaways, it seemed impossible for duckbills to get there.

Silhouette showing the size of Ajnabia compared with humans and the contemporary Maastrichtian dinosaur fauna of Morrocco. ©Dr Nick Longrich.

The discovery of the new fossil in a mine a few hours from Casablanca was “about the last thing in the world you would expect,” said Dr Nicholas Longrich, of the Milner Centre for Evolution at the University of Bath, who led the study. Dr Longrich said: “It was completely out of place, like finding a kangaroo in Scotland. Africa was completely isolated by water – so how did they get there?”

Study of Ajnabia’s distinctive teeth and jawbones show it belonged to Lambeosaurinae, a subfamily of duckbills with elaborate bony head crests. Lambeosaurs evolved in North America before spreading to Asia and Europe, but have never been found in Africa before.

Reconstructing duckbill evolution, they found the lambeosaurs evolved in North America, then spread over a land bridge to Asia. From there, they colonised Europe, and finally Africa.

Because Africa was isolated by deep oceans at the time, duckbills must have crossed hundreds of kilometres of open water- rafting on debris, floating, or swimming – to colonise the continent. Duckbills were probably powerful swimmers – they had large tails and powerful legs, and are often found in river deposits and marine rocks, so they may have simply swum the distance.

“Sherlock Holmes said, once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth,” said Longrich. “It was impossible to walk to Africa. These dinosaurs evolved long after continental drift split the continents, and we have no evidence of land bridges. The geology tells us Africa was isolated by oceans. If so, the only way to get there is by water.”

In reference to this feat, the dinosaur is named “Ajnabia odysseus”. Ajnabi being Arabic for “foreigner”, and Odysseus referring to the Greek seafarer.

Map showing the location of duckbill dinosaurs during the Late Cretaceous period. ©Dr Nick Longrich.

Ocean crossings are rare, improbable events, but have been observed in historic times. In one case, green iguanas travelled between Caribbean islands during a hurricane borne on debris. In another, a tortoise from the Seychelles floated hundreds of kilometres across the Indian Ocean to wash up in Africa.

“Over millions of years,” said Longrich, “Once-in-a-century events are likely to happen many times. Ocean crossings are needed to explain how lemurs and hippos got to Madagascar, or how monkeys and rodents crossed from Africa to South America.”

But the fact that duckbills and other dinosaur groups spread between continents, even with high sea levels, suggests dinosaurs travelled across oceans as well. “As far as I know, we’re the first to suggest ocean crossings for dinosaurs,” said Longrich.

The international team of scientists was led by the University of Bath with researchers from the University of the Basque Country UVP/EHU (Spain), George Washington University (USA) and the Natural History Museum of Sorbonne University (France) / Universite Cadi Ayyad (Morocco).

Dr Nour-Eddine Jalil, from the Natural History Museum of Sorbonne University (France) said: “The succession of improbable events (crossing an ocean by a dinosaur, fossilization of a terrestrial animal in a marine environment) highlights the rarity of our find and therefore its importance.

“Ajnabia shows us that hadrosaurs have set foot on African land, telling us that ocean barriers are not always an insurmountable obstacle.”

References: Nicholas R.Longrich, Nour-Eddine Jalil et al., “The first duckbill dinosaur (Hadrosauridae: Lambeosaurinae) from Africa and the role of oceanic dispersal in dinosaur biogeography”, Science Direct, 2020. https://doi.org/10.1016/j.cretres.2020.104678 https://www.sciencedirect.com/science/article/abs/pii/S0195667120303657?via%3Dihub

Provided by University Of Bath

Paleontology

New Species Of Ancient Cynodont, 220 Million Years Old, Discovered

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Fossilized jaw bone fragments of a rat-like creature found at the Petrified Forest National Park in Arizona last year by a Virginia Tech College of Science Ph.D. candidate are in fact a newly discovered 220-million-year-old species of cynodont or stem-mammal, a precursor of modern-day mammals.

A Photoshop-created image of how Kataigidodon venetus may have looked, illustrated by Ben Kligman, a Ph.D. student in the Department of Geosciences and Hannah R. Kligman. Credit: Virginia Tech

The finding of this new species, Kataigidodon venetus, has been published today in the journal Biology Letters by lead author Ben Kligman, a doctoral student in the Department of Geosciences.

“This discovery sheds light on the geography and environment during the early evolution of mammals,” Kligman said. “It also adds to evidence that humid climates played an important role in the early evolution of mammals and their closest relatives. Kataigidodon was living alongside dinosauromorphs and possibly early dinosaurs related to Coelophysis—a small bipedal predator—and Kataigidodon was possibly prey of these early dinosaurs and other predators like crocodylomorphs, small coyote-like quadrupedal predators related to living crocodiles.”

Kligman added that finding a fossil that is part of Cynodontia, which includes close cousins of mammals, such as Kataigidodon, as well as true mammals, from Triassic rocks is an extremely rare event in North America. Prior to Kligman’s discovery, the only other unambiguous cynodont fossil from the Late Triassic of western North America was the 1990 discovery of a braincase of Adelobasileus cromptoni in Texas. Note that 220 million years ago, modern day Arizona and Texas were located close to the equator, near the center of the supercontinent Pangaea. Kataigidodon would have been living in a lush tropical forest ecosystem.

Kligman made the discovery while working as a seasonal paleontologist at Petrified Forest National Park in 2019. The two fossil lower jaws of Kataigidodon were found in the Upper Triassic Chinle Formation. Because only the lower jaws were discovered and are quite small—half an inch, the size of a medium grain of rice—Kligman only has a semi-picture of how the creature looked, roughly 3.5 inches in total body size, minus the tail.

Along with the jawbone fossils, Kligman found incisor, canine, and complex-postcanine teeth, similar to modern day mammals. Given the pointed shape of its teeth and small body size, it likely fed on a diet of insects, Kligman added. (Why are jaw fossils commonly found, even among small specimens? According to Kligman, the fossil record is “biased” toward only preserving the largest and most robust bones in a skeleton. The other smaller or more fragile bones—ribs, arms, feet—disappear.)

Kligman carried out field work, specimen preparation, CT scanning, conception, and design of the studyand drafting of the manuscript. He added that he and his collaborators only discovered the fossils were of a new species after reviewing the CT scan dataset of the jaws and comparing it to other related species.

“It likely would have looked like a small rat or mouse. If you were to see it in person you would think it is a mammal,” Kligman added. Does it have fur? Kligman and the researchers he worked with to identify and name the creature actually don’t know. “Triassic cynodonts have not been found from geological settings which could preserve fur if it was there, but later nonmammalian cynodonts from the Jurassic had fur, so scientists assume that Triassic ones did also.”

The name Kataigidodon venetus derives from the Greek words for thunderstorm, “kataigidos,” and tooth, “odon,” and the Latin word for blue, “venetus,” all referring to the discovery location of Thunderstorm Ridge, and the blue color of the rocks at this site. Kligman didn’t name the creature, though. That task fell to Hans Dieter-Sues, coauthor and curator of vertebrate paleontology at the Smithsonian National Museum.

Additional collaborators include Adam Marsh, park paleontologist at Petrified Forest National Park, who found the jaw fossils with Kligman, and Christian Sidor, an associate professor at the University of Washington’s Department of Biology. The research was funded by the Petrified Forest Museum Association, the Friends of Petrified Forest National Park, and the Virginia Tech Department of Geosciences.

“This study exemplifies the idea that what we collect determines what we can say,” said Michelle Stocker, an assistant professor of geosciences and Kligman’s doctoral advisor. “Our hypotheses and interpretations of past life on Earth depend on the actual fossil materials that we have, and if our search images for finding fossils only focuses on large-bodied animals, we will miss those important small specimens that are key for understanding the diversification of many groups.”

With Kataigidodon being only the second other unambiguous cynodont fossil from the Late Triassic found in western North America, could there be more new species out there waiting to be found?

Kligman said most likely. “We have preliminary evidence that more species of cynodonts are present in the same site as Kataigidodon, but we are hoping to find better fossils of them,” he added.

References: A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record, Biology Letters (2020). https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0631

Provided by Virginia Tech